1. Field of the Invention
The present invention relates generally to a system for removing environmentally harmful volatile contaminants from saturated or groundwater regions of the soil subsurface. More particularly, the present invention relates to a multiple point adjustable depth air sparging system which uses injected air to remove volatile contaminants from saturated or groundwater regions of the soil's subsurface.
2. Description of the Prior Art
Air sparging is a relatively recent and a very innovative environmental remediation technology that uses air injected under pressure to remove environmentally harmful volatile contaminants from a contaminated groundwater zone within the soil's subsurface. Air sparging systems are capable of removing volatile contaminants such as gasoline, certain solvents and jet fuels from the groundwater region of the soil subsurface. In particular, air sparging systems are used to remove residual source contamination, clean up dissolved phase contamination, and contain a migrating contaminant plume.
Injected air strips and converts the contaminants from a liquid phase to a vapor phase and then transports the volatile contaminants via air channels to an unsaturated zone within the soil's subsurface. The extent of the injected air within the remedial zone of air sparging site affects the level of contact with the target contaminants.
U.S. Pat. No. 6,305,878 for an “Adjustable Depth Air Spargimg Well” discloses a flow through packer which is slidably mounted within a well casing allowing for vertical movement of the flow through packer within the well casing. The flow through packer includes an inflatable packer fabricated from inflatable elastomeric tubing, a lower end portion of an air supply tube which has a plurality of openings for providing pressurized air to inflate the packer, and a pair of elastomer/rubber packer end caps. An air compressor/blower is coupled to the air supply tube supplying pressurized air to the inflatable packer which inflates the packer holding the packer at a fixed depth within the well casing. Deflating the inflatable packer allows for vertical movement of the inflatable packer within the well casing. Positioned at the lower end of the air supply tube is a screen pressure regulator through which air under pressure passes to a well screen. The well screen, which comprises the lower portion of the well casing, is mounted in the soil's saturated zone. The pressurized air next passes through the well screen into the soil's saturation zone removing volatile contaminants and transferring the contaminants to the soil's vadoze zone.
While successful in cleaning up contaminated sites, present systems, such as the system of U.S. Pat. No. 6,305,878, use only one discrete depth air sparge well to inject air into the soil's contaminated groundwater zone. Attempts to mechanically adjust air sparge wells with specialized equipment have met with only limited success.
There is a need to increase the level of air distribution by using multiple injection points to vary air injection depths within the soil's contaminated groundwater zone. At least a second point of air injection is required, preferably at a fixed depth to provide additional air flow channels resulting in the removal of all volatile contaminants from the saturated or ground water regions of the soil subsurface being treated.
There is also a need for a user to have the capability to precisely and repeatedly adjust the depth of air injection without the expense of having to install new air sparging wells.